Best way for sign up process after inviteIt depends on how you shape the jump point from the email to the app. If the link is shaped in such a way as to say 'sign up for our app', or 'start using our app', anything that gets in the way of those goals is poor UX as the user will not be interested in trying out the app first. However if you shape the email to say 'try out our app', then it makes sense to give them a demo. Maybe give them both options in the email? "try our app or sign up right now"?